Microbiological and biochemical aspects of inland Pecorino Abruzzese cheese

摘要

Little is known on physicochemical and biochemical characteristics of “Pecorino” Abruzzese cheese in L’Aquila province, an artisanal cheese produced from ewe raw full-cream milk.Three batches of inland “Pecorino” Abruzzese cheese were examined for microbiological, compositional, biochemical and sensory characteristics at the aim of isolating and storing in a bacterial collection, indigenous strain to preserve the microbial biodiversity present in this cheese, to a possible definition of a PDO. Cheese samples from three dairies, at different stages of production were collected and 148 colonies were characterized. Physicochemical assays, species-specific PCR and 16S rRNA gene sequencing revealed that the majority of the lactic acid bacteria (LAB) isolates were Enterococcus faecium and En. faecalis. They were highly prevalent, accounting for 48% of the isolates. The lactic microflora consisted of lactobacilli and lactococci from the species Lactobacillus plantarum (12.2%), Lactobacillus brevis (10.1%), Lactococcus lactis subsp. cremoris (11.5%), respectively.Urea-PAGE electrophoresis showed extensive degradation of αS1-casein (CN) and moderate hydrolysis of β-CN. Formation of γ-CNs from β-CN were highlighted. RP-HPLC profiles of the ethanol-soluble and ethanol-insoluble fractions of the pH 4.6-soluble nitrogen showed only minor differences between the three farms: lower proteolysis in the soluble fraction than the insoluble.Leucine, glutamic acid, lysine, valine were the free amino acids present at the highest levels in all the cheeses. Flavour and texture profile were characterized through a sensory analysis.